In 1997 it was speculated that a relatively small metallic asteroid with a diameter of 1.6 km (0.99 mi) contains more than
$20 trillion USD worth of industrial and precious metals.
[6][30] A comparatively small
M-type asteroid with a mean diameter of 1 kilometre (0.62 mi) could contain more than two billion metric tons of
iron–
nickel ore,
[31] or two to three times the annual production of 2004.